This invention relates to electric arc welding apparatus, more particularly to an automatic, rotatable welding helmet designed to greatly improve safety and protection of the welder, and at the same time aid in improving his working conditions and workmanship.
In the technology of electric arc welding, systems have been developed to provide an inert gas as a shielding agent around the metals being welded, in order to reduce atmospheric contamination which can reduce overall weld strength and performance. These have become known as Tungsten Inert-Gas, or TIG, and Metal Inert-Gas, or MIG. Both these sytems employ an arc welding circuit which includes a source of electric current, an electrode (in the case of TIG systems being non-consumable and in the case of MIG systems being consumable) and a welding cycle activation switch (in the case of TIG systems being a foot pedal and in the case of MIG systems being a hand trigger) which is used to regulate the inert gas flow and electric current, via a delay circuit, in such manner as to ensure that inert gas has surrounded the work piece before the arc may be struck.
The arc so produced is of an extreme intensity and covers the electromagnetic spectrum both above (ultraviolet) and below (infrared) the frequency of the visible region. These rays are extremely damaging to the eyes; even exposed skin surfaces may experience a sunburning effect as a result of an arc welding session. Consequently, protective means have developed over the years to assure that welders are not put at risk due to long term, intensive welding assignments. These include protective clothing, gloves and welding helmet. The helmet is particularly critical to the welder in terms of the need to cancel any harmful rays and generally protect the face from sparks. In order to achieve this result, opaque hoods which generally cover the face and neck areas are used, having light transmitting, face mounted shields for viewing incorporating very high attenuation characteristics, essentially cancelling all ultraviolet and infrared light and greatly reducing the intensity of transmitted visible light. As a consequence, these helmets, when worn by the welder, prevent him from seeing anything, since room light is insufficient in intensity to permit seeing outside the shield, until an arc is struck; yet these helmets must be worn in advance of striking an arc to prevent injury. This dichotomy has plagued the art since its inception.
Conventional practice among welders has been to position the electrode at the work piece, press the welding cycle activation switch, and, by utilizing a nod of the head, cause the helmet to lower over their face by means of a head band pivot arrangement common in the art. This involves a degree of chance that the arc may prematurely strike, or that the nodding action may cause misalignment of the electrode (which won't be known when the hood is down until the arc strikes and sufficient light permits the welder to see through the face plate).
In the prior art, attempts have been made to devise an automatic safety means to assure that a welder will not be accidentally exposed to the harmful rays of an electric arc. Patent 3,096,430 to Farr, is typical of these previous attempts. There, the face plate is rotatably mounted upon the hood so that it may be alternately moved up out of the way, permitting visual inspection of the job in ordinary room light, and down, thereby assuring that only filtered light reaches the welder's eyes. With the helmet fully down, the foot pedal switch used in TIG systems, or the hand trigger used in MIG systems, is utilized not only to signal to a relay in its usual function of starting the inert gas flow and subsequent current flow to the electrode, but also to signal introduction of compressed air into a piston-cylinder assembly mounted upon the helmet, activating rotary closure of the eye shield (not the hood itself) in advance of striking the arc. This, and previous solutions have failed to address the primary concern of welders: they wish to spend as little time under the hood as possible. Consequently, the present invention solves the need in the art to provide an automatic safety mechanism to prevent eye injury and concomitently minimize under hood time by providing an automatically activated rotatable welding helmet system.
It is, therefore, an object of the invention to provide an automatic safety welding helmet adaptable to existing TIG and MIG welding systems, that provides for minimum time that the welder must spend under the hood.
It is a further object of the invention to provide a fully automatic system utilizing an electrical safety circuit and air control system integrated as one system, having the advantage of a totally adjustable hands off capability.
It is still a further object of the invention to provide a safety system that protects the welder's eyes from harmful electric arc light rays by not allowing the arc cycle to commence until the helmet is in the fully down position.
It is yet a further object of the invention to provide a safety system which reduces welder neck and shoulder fatigue due to elimination of nodding motions used to lower conventional helmet hoods.
It is still a further object of the invention to provide a safety system for arc welding which improves workmanship by: (1) leaving both hands free to position the work piece and the electrode, (2) elimination of flinching at the moment that the arc strikes and higher level of concentration on the job at hand, since worry of accidental striking with the hood still raised is absent, and (3) better working conditions for the welder, since his vision is unrestricted and his personal comfort increased while the hood is up.
These, and additional objects, advantages, features, and benefits of the invention will become apparent from the following specification.